Textile yarn sized with sodium cellulose acetate sulfate



United States Patent O 3,653,696 TEXTlLE YARN SlZED WITH SDlUlVi CELLULOSE ACETATE SULFATE George P. Toney and Donald l. Brown, Kingsport, Tenn.,

assignors to Eastman Kodak Company, Rochester,

N.Y., a corporation of New Jersey No Drawing. Filed Mar. 21, 1950, Ser. No. 16,i97

2 Claims. (Cl. 117-1395) This invention relates to a new sizing agent for -textile yarns. In particular it relates to -a new sizing agent for applying a protective coating to laments, threads or yarns of cellulose esters during their fabrication into cloth.

In the production of textile materials it is necessary to apply a coating or size to the iibers to protect them from abrasion during the Various operations involved in the formation of the cloth. This coating or size must be flexible, tough, and water-soluble. The flexibility and toughness are obvious necessities since ,the fibers, threads or filaments are twisted and bent in various directions and rub against the shuttle of Ithe loom and against other surfaces during the weaving operation. The coating must be water-soluble so that it can be readily removed from the iinished fabric by -a simple scouring operation.

In the ease of cotton, the most commonly used sizing agent for the thread during the weaving of vthe cloth is starch. This `compound is used extensively in many forms such as the hydrolyzed starches, the dextrins, and the partially etheriiied or esteriiied starches containing only a slight amount of the ester or ether substituent group. Examples of lthe latter `are the slightly hydroxyethylated starches Iand the slightly `acetylated starches now commercially available las cotton textile sizes. Also, in the case of cotton such compounds as water-soluble carboxymethyl cellulose, water-soluble hydroxyet'hyl cellulose and the various water-soluble natural gums (guar gum, gum arabic, sodium alginate, etc.) have been used. Thus, a wide variety of water-soluble polymeric materials have been used with varying degrees of success as sizing agents for cotton textiles.

In the case of the cellulose ester fibers, in particular cellulose acetate, |a more diiiicult sizing problem exists. The conventional cotton sizing agents oder little protection to these threads or filaments during processing into cloth. This is because the applied coatings of such products do not adhere tenaciously to cellulose acetate filaments and are therefore scraped away by abrasion.

Among the many water-soluble polymeric materials which have been recommended as a protective size for cellulose acetate yarn during the weaving `operation only a few have ever reached commercial importance. Of these, gelatin and the sodium salt of a maleic acid styrene copolymer are in widespread use. However, gelatin leaves much to be desired as a sizing agent. lt is only sparingly soluble in water at room temperatures and dissolves only slowly in water at 14o-160 F. Gelatin is also diicult to remove completely trom the iinished clo-th by scouring. This results in residual amounts of the size remaining `on the :cloth to 4imp/air its dyeing characteristics. Finally gelatin, being -a natural product, is an excellent source of food for micro-organisms. This must be circumvented by .the use of various preservatives in the size make-up solution prior to its application.

Although the styrene-maleic acid copolymer is a synthetic compound which is not easily attacked by microorganisms, this product `also dissolves rather slowly in hot water and is difficulty removed from the cloth after the weaving oper-ation. Moreover this compound, as well as gelatin, imparts a considerable Iodor to its solutions and to the treated yarn.

We have found that sodium cellulose acetate sulfate is yan excellent size for cellulose acetate yarn. This substance, which is water-soluble, is fa substantially completely esteriiied mixed ester containing the sodium acid sulfate group (-OSO3Na) as the minor ester substituent rand the :acetoxy radical las the major ester substituent. The preparation of sodium cellulose acetate sulfate has been described in U.S. Patents 2,582,009 land 2,622,079. its sulfur content can vary between 5% and 413%, and its acetyl content can vary between 10% and 35%. These values represent ia cellulose Iester with a degree of substitution of 0.4-1.6 sulfate groups and 0.9-2.5 acetyl groups per anhydroglucose unit. The more important value is the sulfur content of the ester, since this represents the amount of water-solubilizing sulfate groups present in the product. Below a sulfur content of 5% the product is not sui'iiciently water-soluble to produce a satisfactory sizing solution. Above a sulfur content of 13% lthe product will not 'adhere tenacious-ly to the yarn. This is ,believed Ito be due to the lo'w amount of acetyl groups present in a sodium cellulose acetate sulfate which is so highily substituted with respect to the sulfate group. rllhe preferred tyne of product for tour purpose has a sulfur content of 741% and fan acetyl content of l5-22%.

Another factor which must be considered is the viscosity of 'the water-soluble sodium cellulose `acetate sullate. The method of controlling this viscosity is disclosed in U.S. Patent 2,622,079, column 3. The degradation of the cellulose during the preparation of the mixed ester must be so controlled that the finished product is capable of producing a ilowable solution of at least 5% concentration :at 25 C. High viscosity types of sodium cellulose Kacetate sulfate therefore are inoperative because only their very dilute solutions Cl-2%) are capable of being free iiowing at room temperatures. The high concentrations of such products form gels which will not flow from the size make-up tank 'and low concentrations (ie. below 2%) do not produce a sufficient `amount of protective lm on ythe iioers to function as a satisfactory size.

The following examples illustrate our invention without limiting it.

Example 1.-A 7% solution :of low viscosity type sodium cellulose acetate `sulfate was used to size some denier 19 iilament cellulose acetate yarn containing ione-third of a turn twist per inch. The sized yarn was then checked for abrasion resistance by both the Duplan 'and the Walker abrasion tests. The Dupl-an test measures the sized yarns ability to withstand sur-iace abrasion, while the Walker test measures the sized yarns ability 'to withstand flexing. As controls, an unsized yarn Aand a yarn treated with a commercial cellulose acetate size solution (a styrene-maleic acid, sodium salt size) were also given the Dupri-an and Walker abrasion tests. Both size solutions contained 6.5% of the sizing agent. The results These results show that the sodium cellulose acetate sulfate .sized yarn had a better abrasion resistance than 'the same yarn .treated with :a standard commercial size. The sodium cellulose acetate sulfate used in this experimen-t had a sulfur content of 9% and an acetyl content of 20%. A 5% solution had a viscosity of 600 c.p.s. at 25 C.

Example 2.-The sized cellulose acetate yarns of Example l were woven into cloth. Both products withstood ythe abrasion of drop Wires, heddle eyes, and reed action during beat up of lthe filling. There was no evidence of the sizing agent aking off in either case. However, the cloth with the sodium cellulose acetate sulfate size could be scoured in half the time required for the cloth containing `the commercial size.

The Duplan `abrasion :test is carried out on a Duplan Cohesion Tester, which is a machine designed to test the effectiveness of a slashing solution by ltesting the cohesion of the sized filament yarn before the warp reaches the loom. Samples of sized yarn under a constant tension are abraded by friction plates moving back and foh on the yarn at a constant rate. The :average number of strokes per strand required to separate the laments in yten strands of yarn `are reported 4as the Duplan value. Forty tests on each sample are considered the standard itest. In examining the strands lat intervals for open places, au air jet is blown along each strand to assist in detecting openings.

The Walker abrasion test is carried out on a Walker Abrader machine, which is ia machine designed to measure the comparative abrasion resistance of strands of yarn. This test applies a controlled amount of localized Wear `or rubbing between strands of yarn. is repeated at regular intervals `until breaking occurs, and the number of strokes to failure is taken as `a measure of the wearing qualities. The machine is constructed to This rubbing 25 ytest 24 individual specimens `of yarn at one time, which allows for variations, and an average of the cycles to failure on 20 specimens is reported as the Walker Abrasion Value. This test is discussed by Tanenhous in Textile Research J. 17, 281 (1947).

We claim:

1. A cellulose acetate `textile yarn carrying a sizing of a sodium cellulose acetate sulfate, said sodium cellulose acetate sulfate being -a substantially completely esteriied mixed cellulose ester containing sodium acid sulfate groups and acetoxy radicals as ester substituents and which has a degree of substitution of 0.4-1.6 sulfate groups `and 0942.5 acetyl groups per anhydroglucose unit.

2. A cellulose acetate :textile yarn carrying a sizing of sodium cellulose acetate sulfate, said sodium cellulose `acetate sulfate being a substantially completely esten'ed mixed cellulose ester containing sodium acid sulfate groups `and acetoXy radicals as ester substituents and which has a sulfur content of from about 7% to 11% and an `acetyl content of from about 15% :to 22%.

References Cited in the file of this patent UNITED STATES PATENTS 1,950,664 Dreyfus et al. Mar. 13, 1934 2,134,895 Seymour et al Nov. 1,1938 2,622,079 Crane Dec. 16, 1952 

1. A CELLULOSE ACETATE TEXTILE YARN CARRYING A SIZING OF A SODIUM CELLULOSE ACETATE SULFATE, SAID SODIUM CELLULOSE ACETATE SULFATE BEING A SUBSTANTIALLY COMPLEELY ESTERIFIED MIXED CELLULOSE ESTER CONTAINING SODIUM ACID SULFATE GROUPS AND ACETOXY RADICALS AS ESTER SUBSTITUENTS AND WHICH HAS A DEGREE OF SUBSTITUTION OF 0.4-1.6 SULFATE GROUPS AND 0.9-2.5 ACETYL GROUPS PER ANHYDROGLUCOSE UNIT. 